Solar System Log by Andrew Wilson, published 1987 by Jane's Publishing Co. Ltd.

Lunar Orbiter 3 was the final Lunar Orbiter mission to study potential Apollo landing sites; further missions would be dedicated to scientific and global surveys.

The spacecraft arrived in lunar orbit on 7 February 1967. Initial orbital parameters were 200 x 1,850 kilometers at 21° inclination. During its eight-month mission, the spacecraft took 211 frames of pictures, although only 182 were actually returned to Earth because of a problem on 24 February with the motor that rewound the film.

Despite the minor glitch, Lunar Orbiter fulfilled its original mission objectives, returning images of 15.5 million square kilometers of the near side and 650,000 square kilometers of the far side.

On 30 August 1967, ground controllers commanded the vehicle to circularize its orbit to 160 kilometers in order to simulate an Apollo trajectory.

Later, on 9 October 1967, the probe was intentionally crashed onto the lunar surface at 14°36' north latitude and 91°42' west longitude. The photographs from the first three Lunar Orbiters allowed NASA scientists to pick eight preliminary landing sites for Apollo by early April 1967, including site 2 in the Sea of Tranquility, where Apollo 11 would land, and site 5 in the Ocean of Storms, where Apollo 12 (and also Surveyor 3) would disembark.

Key Dates

5 Feb 1967: Launch

9 Oct 1967: End of Lunar Mission

Status: Successful

Fast Facts

Lunar Orbiter 3 helped in the selection of landing sites for Apollo 11 (right) and 12.

Mission controllers also used the spacecraft to simulate the trajectory of Apollo missions.

It was deliberately crashed into the Moon at the end of its mission to avoid potential communication interference.